In general, automotive drivelines transmit torque from an engine and eventually to a set of wheels. Automotive drivelines, such as all-wheel drive (AWD) drivelines, sometimes include power transfer units (PTUs), final drive units (FDUs), rear drive units (RDUs), or a combination of these units to transmit the torque. The exact units in a particular automotive driveline often depends on the location of the engine and on the location of the accompanying transmission. The PTUs, FDUs, and RDUs typically include gears, shafts, bearings, seals, and other components. Lubricant held in a unit ordinarily makes its way to some of its components when the lubricant is sloshed and splashed about amid use of the unit. The lubricant is used to both lubricate and cool components.
Further, the PTUs, FDUs, and RDUs can be equipped with disconnect and re-connect capabilities in which disconnected components are no longer driven to transmit torque between them. The capabilities preclude driven torque in regions of the automotive drivelines not needing torque at a particular time. For instance, on-demand AWD drivelines do not always transmit torque among all of its shafts at all times. Disconnect and re-connect capabilities have been shown to enhance fuel efficiency, reduce emissions, and provide yet additional performance improvements.
Providing proper lubrication to unit components with disconnect and re-connect capabilities has presented challenges. It has been found, for instance, that the disconnected components no longer slosh and splash the lubricant about since the components are no longer spinning in this state, or at least are not spinning as they did in the connected state. As a consequence, when disconnected, lubricant might not always make its way to some of the unit's components.